A zipper clause is a clause in an employment agreement in which
both parties waive the right to demand bargaining on any matter not dealt
with in the contract, regardless of whether that matter was contemplated
when the contract was negotiated or signed. A zipper clause in a written
contract makes it clear that only the promises contained in that writing
are part of the employment relationship.

The following is an example of a zipper clause:

"All matters within the scope of bargaining have been negotiated and
agreed upon. The terms and conditions set forth in this Agreement represent
the full and complete understanding and commitment between the District
and the Association."